Optimal Asynchronous Garbage Collection for RDT Checkpointing Protocols

Communication-induced checkpointing protocols that ensure rollback-dependency trackability (RDT) guarantee important properties to the recovery system without explicit coordination. However, to the best of our knowledge, there was no garbage collection algorithm for them which did not use some type of process synchronization, like time assumptions or reliable control message exchanges. This paper addresses the problem of garbage collection for RDT checkpointing protocols and presents an optimal solution for the case where coordination is done only by means of timestamps piggybacked in application messages. Our algorithm uses the same timestamps as off-the-shelf RDT protocols and ensures the tight upper bound on the number of uncollected checkpoints for each process during all the system execution

Optimal Asynchronous Garbage Collection for Checkpointing Protocols with Rollback-Dependency Trackability

Communication-induced checkpointing protocols that ensure rollback-dependency trackability (RDT) guarantee important properties to the recovery system without explicit coordination. However, to the best of our knowledge, there was no garbage collection algorithm for them which did not use some type of process synchronization, like time assumptions or reliable control message exchanges. This paper addresses the problem of garbage collection for RDT checkpointing protocols and presents an optimal solution for the case where coordination is done only by means of timestamps piggybacked in application messages. Our algorithm uses the same timestamps as off-the-shelf RDT protocols and ensures the tight upper bound on the number of uncollected checkpoints for each process during all the execution

Using Common Knowledge to Improve Fixed-Dependency-After-Send

Checkpoint patterns that enforce the rollback-dependency trackability (RDT) property allow ecient solutions to the determination of consistent global checkpoints that include a given set of checkpoints. Fixed-Dependency-After-Send (FDAS) is a well-known RDT protocol that forces the dependency vector of a process to remain unchanged during a checkpoint interval after the rst message-send event. In this paper, we explore processes' common knowledge about their behavior to derive a more ecient condition to induce checkpoints under FDAS. We consider that our approach can be used to improve other RDT checkpointing protocols

A Linear Approach to Enforce the Minimal Characterization of the Rollback-Dependency Trackability Property

A checkpointing protocol that enforces rollback-dependency trackability (RDT) during the progress of a distributed computation must take forced checkpoints to break non-trackable dependencies. Breaking just non-visibly doubled dependencies instead of breaking all non-trackable dependencies leads to fewer forced checkpoints, but seemed to require the processes of a computation to maintain and propagate O(n ) control information

RDTPartner: An efficient checkpointing protocol that enforces rollback-dependency trackability

Checkpoint patterns that enforce rollback-dependency trackability (RDT) have only on-line trackable checkpoint dependencies and allow efficient solutions to the determination of consistent global checkpoints. The design of RDT checkpointing protocols that are efficient both in terms of the number of forced checkpoints and in terms of the data structures propagated by the processes is a very interesting research topic. Fixed-Dependency-After-Send (FDAS) is an RDT protocol based only on vector clocks, but that takes a high number of forced checkpoints. The protocol proposed by Baldoni, Helary, Mostefaoui and Raynal (BHMR) takes less forced checkpoints than FDAS, but requires the propagation of an Ç Ò matrix of booleans. In this paper, we introduce a new RDT protocol, called RDT-Partner, in which a process can save forced checkpoints in comparison to FDAS during checkpoint intervals in which the communication is bound to a pair of processes; a very interesting optimization in the context of client-server applications. Although the data structures required by the proposed protocol maintain the Ç Ò complexity of FDAS, theoretical and simulation studies show that it takes virtually the same number of forced checkpoints than BHMR

Systematic Analysis of Index-Based Checkpointing Algorithms using Simulation

Index-based checkpointing allows the use of simple and efficient algorithms for domino -effect free construction of recovery lines. In this paper, we use a simulation toolkit to analyze the behavior of index-based algorithms. We present a performance study of the well-known algorithm proposed by Briatico, Ciuffoletti, and Simoncini and explore the impact of some optimizations of this algorithm presented in the literature. Our results indicate that an expensive and complex optimization may not reduce the number of forced checkpoints in comparison to a simpler optimization. Keywords: distributed checkpointing, rollback recovery, logical clocks, simulation of distributed systems.

Better safe than sorry: a vehicular traffic re-routing based on traffic conditions and public safety issue

Vehicular traffic re-routing is the key to provide better traffic mobility. However, taking into account just traffic-related information to recommend better routes for each vehicle is far from achieving the desired requirements of proper transportation management. In this way, context-aware and multi-objective re-routing approaches will play an important role in traffic management. Yet, most procedures are deterministic and cannot support the strict requirements of traffic management applications, since many vehicles potentially will take the same route, consequently degrading overall traffic efficiency. So, we propose an efficient algorithm named as Better Safe Than Sorry (BSTS), based on Pareto-efficiency. Simulation results have shown that our proposal provides a better trade-off between mobility and safety than state-of-the-art approaches and also avoids the problem of potentially creating different congestion spots101CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQNão te